The Volokh Conspiracy's Jonathan Adler points to George Will's recent column on the polar bear listing for support of the proposition that "some conservative complaints are overstated. There is little risk that the federal government, or even a wayward federal judge, will hold that some power plant or other large greenhouse gas emitter is guilty of 'taking' polar bears in violation of the ESA. As broad as the ESA's take prohibition may be, it has never been interpreted to reach such attenuated private harm."
Then again, up until the listing, the federal government had never cited global warming in justifying a endangered/threatened species classification, nor had it been the normal practice of the government to list an overall thriving species. Moreover, and contrary to Professor Adler's suggestion, counting on the courts to limit the reach of the polar bear listing is indeed quite risky.